US Attorney General Jeff Sessions has denounced as "an appalling and detestable lie" the idea that he colluded with Russian meddling in the 2016 presidential campaign but refused to answer a series of questions during a high-stakes Senate hearing.
Mr Sessions, a senior member of Republican President Donald Trump's Cabinet and an adviser to his presidential campaign, faced criticism from Democratic senators for declining to answer their questions relating to conversations he had with Mr Trump.
Democratic Senator Martin Heinrich accused Mr Sessions of violating his vow to tell the full truth.
He told Sessions "Youre impeding this investigation."
Mr Sessions dodged questions about whether he had discussed then-FBI director James Comey's handling of the FBI's Russia probe with Mr Trump before the president fired Mr Comey on 9 May.
Similarly, he did not answer whether Mr Trump had expressed concern to Mr Sessions about his March decision to recuse himself from the Russia investigation.
Democratic Senator Ron Wyden told Mr Sessions, "I believe the American people have had it with stonewalling. Americans don't want to hear that answers to relevant questions are privileged."
"I am not stonewalling," Mr Sessions replied. "I am following the historic policies of the Department of Justice."
Mr Sessions said he would not discuss confidential communications with the president.
Senator Angus King, an independent, questioned Mr Sessions' legal basis for refusing to answer. Mr Sessions said Mr Trump had not invoked executive privilege regarding the conversations.
Executive privilege is a power that can be claimed by a president or senior executive branch officials to withhold information from Congress or the courts to protect the executive branch decision-making process.
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US intelligence agencies concluded in a report released in January that Russian President Vladimir Putin ordered an effort to interfere in the election to help Mr Trump in part by hacking and releasing damaging emails about Democratic candidate Hillary Clinton.
The testimony by Mr Sessions marked the latest chapter in a saga that has dogged Mr Trump's first five months as president and distracted from his domestic policy agenda, including major healthcare and tax cut initiatives.
"I have never met with or had any conversation with any Russians or any foreign officials concerning any type of interference with any campaign or election in the United States. Further, I have no knowledge of any such conversations by anyone connected with the Trump campaign," Mr Sessions said.
"The suggestion that I participated in any collusion or that I was aware of any collusion with the Russian government to hurt this country, which I have served with honor for over 35 years, or to undermine the integrity of our democratic process, is an appalling and detestable lie," he said.
Mr Sessions is the most senior member of Mr Trump's administration caught up in the controversy over whether associates of the president colluded with Russia to help Mr Trump win the election.
